2000—2017年中国区域地表反照率变化及其影响因子

Variations of land surface albedo and its influencing factors in China from 2000 to 2017

在全球气候变暖的背景下,地表反照率已成为地表辐射平衡和气候研究的重要参数之一。利用中国陆地生态系统研究网络(Chinese Ecosystem Research Network,CERN)提供的34个站点辐射数据、GLASS地表反照率产品、ERA-Interim再分析资料、MODIS EVI(MOD13A3)和中国气象数据共享网提供的气象数据,基于Sen’s Slope趋势分析方法,分析不同生态系统地表反照率的变化特征;利用全子集回归和分层分解方法计算地表反照率与各要素之间的相关性和相对重要性;探讨各气候因子对地表反照率的影响。结果表明,2000—2017年裸土地和裸岩砾石地变化率最大,冬季斜率达-0.083%yr-1。生长季地表反照率与降水、增强型植被指数(Enhanced Vegetation Index,EVI)、土壤水分和气温显著相关的像元分别占总像元的73%、79%、56%和86%。EVI是干旱和半干旱地区地表反照率变化的主导因素,其对地表反照率变化的独立贡献率分别为41%和56.18%。7月东北地区降水量和气温对地表反照率的影响大约滞后2个月;内蒙古沙漠地区和长江中下游平原土壤水分对地表反照率的影响大约滞后1~2个月。

In the context of global warming,land surface albedo has become one of the important input parameters for climate simulation.The radiation data of 34 sites provided by Chinese Ecosystem Research Network(CERN),GLASS land surface albedo products,ERA-Interim reanalysis data,MODIS EVI(MOD 13A3)and meteorological data provided by China Meteorological Administration were used to analyze the variation characteristics of the land surface albedo in different ecosystems based on Sen's Slope trend analysis;correlations and relative importance between land surface albedo and climate variables were calculated using allsubsets regression and hierarchical partitioning methods.The results showed that the bare land and rock or gravel land had the largest slope value from 2000 to 2017,being-0.083%yr 1 in winter.Pixels with significant correlations between land surface albedo and precipitation,EVI,soil moisture,and temperature during the growing season accounted for 73%,79%,56%,and 86%of the total pixels,respectively.EVI was the dominant factor in the change of land surface albedo in arid and semi-arid regions,and the independent contribution rates of these two types of regions were 41%and 56.18%,respectively.The effects of precipitation and temperature on land surface albedo in Northeast China in July lagged about 2 months.The influence of soil moisture on land surface albedo lagged about 1-2 months in the desert areas of Inner Mongolia and Middle-Lower Yangtze River Plain.